Alpha-Amylases (alpha-1,4-glucan-4-glucanohydrolases, E.C. 3.2.1.1) constitute a group of enzymes, which catalyze hydrolysis of starch and other linear and branched 1,4-glucosidic oligo- and polysaccharides.
In modern and industrial biotechnology high protein concentrations are achieved during fermentation, purification, recovery and in product formulation.
During the fermentation the protein concentration depend on the host cell used. In industrial processes the protein concentration typically lies from above 0.1 g/liter fermentation broth. For high yield recombinant production of alpha-amylases in Bacillus sp. the protein concentration may be as high as 250 g/liter fermentation broth. After purification the protein concentration may reach levels of about 1000 g/liter.
Such high concentrations leads to an undesirable precipitation resulting in lose of active protein. The tendency today is towards products of increasing strength, which make the ability to maintain the enzyme in solution of increasing importance. Often up-concentration of a protein solutions results in protein precipitates, which are difficult to dissolve into active protein.
Thus, it is the object of this application to provide alpha-amylases with altered properties as defined below, in particular increased solubility.